Encyclopedia of Espionage, Intelligence, and Security

Nanotechnology

█ K. LEE LERNER

Defense programs in many countries are now concentrating on nanotechnology
research that will facilitate advances in such technology used to create
secure but small messaging equipment, allow the development of smart
weapons, improve stealth capabilities, aid in developing specialized
sensors (including bio-inclusive sensors), help to create self-repairing
military equipment, and improve the development and delivery mechanisms
for medicines and vaccines.

Nanotechnology builds on advances in microelectronics during the last
decades of the twentieth century. The miniaturization of electrical
components greatly increased the utility and portability of computers,
imaging equipment, microphones, and other electronics. Indeed, the
production and wide use of such commonplace devices such as personal
computers and cell phones was absolutely dependent on advances in
microtechnology.

Despite these fundamental advances there remain real physical constraints
(e.g., microchip design limitations) to further miniaturization based upon
conventional engineering principles. Nanotechnologies intend to
revolutionize components and manufacturing techniques to overcome these
fundamental limitations. In addition, there are classes of biosensors and
feedback control devices that require nanotechnology
because—despite advances in microtechnology—present
components remain too large or slow.

Advances in Nanotechnology

Nanotechnology advances affect all branches of engineering and science
that deal directly with device components ranging in size between
1/10,000,000 (one ten millionth of a millimeter) and 1/10,0000 millimeter.
At these scales, even the most sophisticated microtechnology-based
instrumentation is useless. Engineers anticipate that advances in
nanotechnology will allow the direct manipulation of molecules in
biological samples (e.g., proteins or nucleic acids) paving the way for
the development of new materials that have a biological component or that
can provide a biological interface.

In addition to new tools, nanotechnology programs advance practical
understanding of quantum physics. The internalization of quantum concepts
is a necessary component of nanotechnology research programs because the
laws of classical physics (e.g., classical mechanics or generalized gas
laws) do not always apply to the atomic and near-atomic level.

Nanotechnology and quantum physics.
Quantum theory and mechanics describe the relationship between energy and
matter on the atomic and subatomic scale. At the beginning of the
twentieth century, German physicist Maxwell Planck (1858–1947)
proposed that atoms absorb or emit electromagnetic radiation in bundles of
energy termed quanta. This quantum concept seemed counter-intuitive to
well-established Newtonian physics. Advancements associated with quantum
mechanics (e.g., the uncertainty principle) also had profound implications
with regard to the philosophical scientific arguments regarding the
limitations of human knowledge.

Planck's quantum theory, which also asserted that the energy of
light (a photon) was directly proportional to its frequency, proved a
powerful concept that accounted for a wide range of physical phenomena.
Planck's constant relates the energy of a photon with the frequency
of light. Along with the constant for the speed of light, Planck's
constant (
h
= 6.626 x 10
−34
Joule-second) is a fundamental constant of nature.

Prior to Planck's work, electromagnetic radiation (light) was
thought to travel in waves with an infinite number of available
frequencies and wavelengths. Planck's work focused on attempting to
explain the limited spectrum of light emitted by hot objects. Danish
physicist Niels Bohr (1885–1962) studied Planck's quantum
theory of radiation and worked in England with physicists J. J. Thomson
(1856–1940), and Ernest Rutherford (1871–1937) to improve
their classical models of the atom by incorporating quantum theory. During
this time, Bohr developed his model of atomic structure. According to the
Bohr model, when an electron is excited by energy it jumps from its ground
state to an excited state (i.e., a higher energy orbital). The excited
atom can then emit energy only in certain (quantized) amounts as its
electrons jump back to lower energy orbits located closer to the nucleus.
This excess energy is emitted in quanta of electromagnetic radiation
(photons of light) that have exactly the same
energy as the difference in energy between the orbits jumped by the
electron.

The electron quantum leaps between orbits proposed by the Bohr model
accounted for Plank's observations that atoms emit or absorb
electromagnetic radiation in quanta. Bohr's model also explained
many important properties of the photoelectric effect described by Albert
Einstein (1879–1955). Einstein assumed that light was transmitted
as a stream of particles termed photons. By extending the well-known wave
properties of light to include a treatment of light as a stream of
photons, Einstein was able to explain the photoelectric effect.
Photoelectric properties are key to regulation of many microtechnology and
proposed nanotechnology level systems.

In the 1920s, the concept of quantization and its application to physical
phenomena was further advanced by more mathematically complex models based
on the work of the French physicist Louis Victor de Broglie
(1892–1987) and Austrian physicist Erwin Schrödinger
(1887–1961) that depicted the particle and wave nature of
electrons. De Broglie showed that the electron was not merely a particle
but a waveform. This proposal led Schrödinger to publish his wave
equation in 1926. Schrödinger's work described electrons as
a "standing wave" surrounding the nucleus, and his system of
quantum mechanics is called wave mechanics. German physicist Max Born
(1882–1970) and English physicist P. A. M. Dirac (1902–1984)
made further advances in defining the subatomic particles (principally the
electron) as a wave rather than as a particle and in reconciling portions
of quantum theory with relativity theory.

Working at about the same time, German physicist Werner Heisenberg
(1901–1976) formulated the first complete and self-consistent
theory of quantum mechanics. Matrix mathematics was well established by
the 1920s, and Heisenberg applied this powerful tool to quantum mechanics.
In 1926, Heisenberg put forward his uncertainty principle which states
that two complementary properties of a system, such as position and
momentum, can never both be known exactly. This proposition helped cement
the dual nature of particles (e.g., light can be described as having both
wave and particle characteristics). Electromagnetic radiation (one region
of the spectrum that comprises visible light) is now understood to have
both particle and wave like properties.

In 1925, Austrian-born physicist Wolfgang Pauli (1900–1958)
published the Pauli exclusion principle states that no two electrons in an
atom can simultaneously occupy the same quantum state (i.e., energy
state). Pauli's specification of spin (+
1
/
2
or −
1
/
2
) on an electron gave the two electrons in any suborbital differing
quantum numbers (a system used to describe the quantum state) and made
completely understandable the structure of the periodic table in terms of
electron configurations (i.e., the energy-related arrangement of electrons
in energy shells and suborbitals).

In 1931, American chemist Linus Pauling published a paper that used
quantum mechanics to explain how two electrons, from two different atoms,
are shared to make a covalent bond between the two atoms. Pauling's
work provided the connection needed in order to fully apply the new
quantum theory to chemical reactions.

Advances in nanotechnology depend upon an understanding and application of
these fundamental quantum principles. At the quantum level the smoothness
of classical physics disappears and nanotechnologies are predicated on
exploiting this quantum roughness.

Applications

The development of devices that are small, light, self-contained, use
little energy and that will replace larger microelectronic equipment is
one of the first goals of the anticipated nanotechnology revolution. The
second phase will be marked by the introduction of materials not feasible
at larger than nanotechnology levels. Given the nature of quantum
variance, scientists theorize that single molecule sensors can be
developed and that sophisticated memory storage and neural-like networks
can be achieved with a very small number of molecules.

Traditional engineering concepts undergo radical transformation at the
atomic level. For example, nano-technology motors may drive gears, the
cogs of which are composed of the atoms attached to a carbon ring.
Nanomotors may themselves be driven by oscillating magnetic fields or high
precision oscillating lasers.

Perhaps the greatest promise for nanotechnology lies in potential
biotechnology advances. Potential nano-level manipulation of DNA offers
the opportunity to radically expand the horizons of genomic medicine and
immunology. Tissue-based biosensors may unobtrusively be able to monitor
and regulate site-specific medicine delivery or regulate physiological
processes. Nanosystems might serve as highly sensitive detectors of toxic
substances or used by inspectors to detect traces of biological or
chemical weapons.

In electronics and computer science, scientists assert that
nanotechnologies will be the next major advance in computing and
information processing science. Microelectronic devices rely on
recognition and flips in electron gating (e.g. where differential states
are ultimately represented by a series of binary numbers
["0" or "1"] that depict voltage states). In
contrast, future quantum processing will utilize the identity of quantum
states as set forth by quantum numbers. In quantum cryptography systems
with the ability to decipher encrypted information will rely on precise
knowledge of manipulations used to achieve various atomic states.

Nanoscale devices are constructed using a combination of fabrication
steps. In the initial growth stage, layers of semiconductor materials are
grown on a dimension limiting substrate. Layer composition can be altered
to control electrical and/or optical characteristics. Techniques such as
molecular beam epitaxy (MBE) and metallo-organic chemical vapor deposition
(MOCVD) are capable of producing layers of a few atoms thickness. The
developed pattern is then imposed on successive layers (the pattern
transfer stage) to develop desired three dimensional structural
characteristics.

Nanotechnology Research

In the United States, expenditures on nanotechnology development tops $500
million per year and is largely coordinated by the National Science
Foundation and Department of Defense Advanced Research Projects Agency
(DARPA) under the umbrella of the National Nano-technology Initiative.
Other institutions with dedicated funding for nanotechnology include the
Department of Energy (DOE) and National Institutes of Health (NIH).

Research interests.
Current research interests in nano-technology include programs to develop
and exploit nanotubes for their ability to provide extremely strong bonds.
Nanotubes can be flexed and woven into fibers for use in
ultrastrong—but also ultralight—bulletproof vests. Nanotubes
are also excellent conductors that can be used to develop precise
electronic circuitry.

Other interests include the development of nanotechnology-based sensors
that allow smarter autonomous weapons capable of a greater range of
adaptations enroute to a target; materials that offer stealth
characteristics across a broader span of the electromagnetic spectrum;
self-repairing structures; and nanotechnology-based weapons to
disrupt—but not destroy—electrical system infrastructure.